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By J. W. Pamplin

Some 40 miles east of Tampa is the center of the Florida pebble phosphate deposits. These are of Pliocene age and consist of several members of the Bone Valley formation.1 Physically the phosphate-bearing formation, locally called the "matrix," varies in thickness from nothing to about 25 ft., usually averages 10 ft., and consists mainly of clay, quartz and phosphate pebble, the latter particles varying in size from colloidal to one inch diameter. The pebbles range in color from dark gray, through white, to cream, and in hardness from that which must be broken with a hammer to that which can be scratched with the fingernail. They assay from 66 to 80 per cent bone phosphate of lime (called "B.P.L." in the trade) or tricalcium phosphate (Ca³P2O8) and are secondary apatites. They form from 15 to 50 per cent by weight of the matrix. Over the matrix lies a varying thickness (5 to 40 ft.) of overburden composed of quartz and clay. Briefly, mining consists of two operations2 in open pits about 200 ft. wide by 1/2 mile or more in length. In the first step overburden is removed by large electric draglines at the rate of about 700 cu. yd. per hour. This is followed closely by hydraulic mining of the matrix at the rate of about 300 cu. yd. per hour. This matrix yardage is moved from an improvised sump in the floor of the pit to an ore-dressing plant, sometimes a mile distant, by one, two or three "pit-cars" (pumping units) working on a 12-in. pipe line called the "rock line" to distinguish it from the high-pressure water line feeding the hydraulic giants, which is known as the "hydraulic line." This 700 yd. of overburden and 300 yd. of matrix—1000 yd. in all-amounts to about 1500 tons of material moved each hour. The overburden is dumped into the mined-out pit alongside the pit being mined. The matrix moves to the ore-dressing plant at the rate of about 7% long tons in 4000 gal. of water per minute—a ratio of approximately one to two by weight, or one to six by volume. This constitutes the "mill heads," but in the pebble district it is called the "matrix."

Jan 1, 1938

By J. Pinto, F. Galasso

THE current emphasis in preparing boron fibers by reduction of gaseous boron compounds on a resistively heated metal wire substrate has renewed interest in the borides of those metals which have relatively high melting points and are available as fine wires. A knowledge of the structures and properties of the borides, which are formed when boron diffuses into the metal core during boron deposition, can be of assistance in the understanding of the boron fiber formation process and the fiber properties. Many of these borides are well-known and their properties have been measured. However, when an unidentified boride is found in the core, it may be difficult to establish its composition because of the small amount of material available, the preferred orientation effects on the reflections in its X-ray pattern, and the possible overlap of X-ray reflections if several borides are present in the core. For example. the proper indexing of the X-ray pattern of WB4, which was formed in the tungsten substrate core during boron fiber formation, was accomplished only after small single crystals of this boride were grown and X-ray precession investigations were conducted.' This note presents the results of a study of the phases formed in the core when tungsten, tantalum, and molybdenum metal wires were used as substrates in the boron fiber preparation process with particular emphasis on the identification and characterization of a higher boride of molybdenum analogous to WB,. Boron was deposited on resistively heated stationary 0.0012-in.-diam tantalum, tungsten, and molybdenum wires at 1050°C for various times up to 60 sec using boron trichloride and hydrogen as the reactant gases. After 60 sec of boron deposition the fibers were approximately 0.006 in. in diam. Examination of photomicrographs of fiber cross sections showed that the boron had diffused nearly to the center of the tungsten and molybdenum cores in 15 and 30 sec, respectively, and only halfway to the center of the tantalum core in 60 sec. X-ray diffraction photographs of the fibers indicated that it was also after 15 and 30 sec deposition times that the tungsten and molybdenum metal reflections, respectively, had disappeared from the X-ray patterns of the fibers. The patterns of the boron fibers produced using tantalum wire as a substrate showed that amorphous boron, TaB2, and tantalum metal were present after a few seconds deposition time and remained even after deposition times of 60 sec. Until a deposition time of 15 sec was reached, the tungsten substrate fibers contained amorphous boron,273 6WB, W2B5, and WB4 as well as tungsten metal, while the molybdenum substrate fibers contained amorphous boron, MoBa, Mo2B5, and molybdenum metal for deposition times up to 30 sec. Just before the molybdenum metal pattern disappeared, a pattern similar to that of WB, appeared, suggesting that a phase, MOB,, isomorphous with WB,, was present in the fiber. This same pattern was obtained from the product formed by heating a mixture of molybdenum metal and excess boron powder in a boron nitride crucible at 1960°C in an argon atmosphere. As was the case with the WBn pattern, this pattern could best be indexed on the basis of a hexagonal unit cell rather than the tetragonal unit cell Chrktien and Helgorsky reported for ~0~4,~ see Table I. The unit cell parameters for MoB4 were calculated to be a, = 5.214A, co = 6.358A. Assuming the space group P63/mmc and positions5 2M01 in 2b and 2MoII in 2c found for tungsten in WB~,' a logical structure for MOB, was determined using geometrical considerations to place the boron

Jan 1, 1969

By J. W. Pamplin

SOME 40 miles east of Tampa is the center of the Florida pebble phosphate deposits. These are of Pliocene age and consist of several members of the Bone Valley formation.1 Physically the phosphate-bearing formation, locally called the "matrix," varies in thickness from nothing to about 25 ft., usually averages 10 ft., and consists mainly of clay, quartz and phosphate pebble, the latter particles varying in size from colloidal to one inch diameter. The pebbles range in color from dark gray, through white, to cream, and in hardness from that which must be broken with a hammer to that which can be scratched with the fingernail. They assay from 66 to 80 per cent bone phosphate of lime (called "B.P.L." in the trade) or tricalcium phosphate (Ca3P20s) and are secondary apatites. They form from 15 to 50 per cent by weight of the matrix, Over the matrix lies a varying thickness (5 to 40 ft.) of overburden composed of quartz and clay. Briefly, mining consists of two operations2 in open pits about 200 ft. wide by ½ mile or more in length. In the first step overburden is removed by large electric draglines at the rate of about 700 cu. yd. per hour. This is followed closely by hydraulic mining of the matrix at the rate of about 300 cu. yd. per hour. This matrix yardage is moved from an improvised sump in the floor of the pit to an ore-dressing plant, some-times a mile distant, by one, two or three "pit-cars" (pumping units) working on a 12-in. pipe line called the "rock line" to distinguish it from the high-pressure water line feeding the hydraulic giants, which is known as the "hydraulic line." This 700 yd. of overburden and 300 yd. of matrix-1000 yd. in all-amounts to about 1500 tons of material moved each hour. The over-burden is dumped into the mined-out pit alongside the pit being mined. The matrix moves to the ore-dressing plant at the rate of about 7 ½ long tons in 4000 gal. of water per minute-a ratio of approximately one to two by weight, or one to six by volume. This constitutes the "mill heads," but in the pebble district it is called the "matrix."

Jan 1, 1938

By S. Stutz

Three years ago, at the Philadelphia meeting, in February, 1881, the author had the pleasure of presenting to the Institute a paper on coal-washing machinery.* Since that time many new machines, with important improvements and labor-saving apparatus, have been introduced, the construction and description of which may be of interest to some of the members of the Institute. By referring to the above-mentioned paper, and more especially to Plate IV., representing a vertical section of a coal-washer, it will be noticed that the bottom of the plunger-box B is made level or horizontal, and supports a spring-buffer F for the purpose of limiting the down-stroke of the plunger P and receiving the impacts of the latter. Althongh the construction of the box, in view of these impacts, received from the start the proper attention (the bottom of the chamber 3 being made of three thicknesses of 3-inch planks, resting on 6-inch sqnare columns), yet, through careless working of the machinery, without the necessary water in the box, it proved in several instances not strong enough, and had to be changed. To prevent such interruptions in future, it became necessary to devise some means for relieving the machine from the impacts of the plunger altogether. This has been accomplished by the arrangement shown upon Plate I. of this paper, representing a new waesher; and not only has the difficulty been overcome, but also sorne other advantages have been obtained, as will be seen further on. The compartments +, A' of the separator-box have been set upon heavy cast-iron brackets B, leaving sufficient space below the bottom for the buffer F and the sediment-valve K. By means of the plunger-rod 6 passing through the stuffing-box s to the outside, and provided at its lower end with a shoe a, the impacts of the plunger are now transmitted from the buffer F directly to the foundation. At the same time a better guide for the plunger P in its up and down movement has been obtained. The plunger of the former machine had only the guide I and the yoke Y, whereas the new machine has an additional guide in the stuffing-box s, thus preventing wear and friction of the plunger against the lining of the box. Further-

Jan 1, 1884

By E. Mcl. Tittmann

Deep-seated human instincts urge us to positively mark the passage of time. We celebrate the passage of each year. Years give way to decades, and decades to half centuries and centuries. At all these mileposts we are inclined to pause, take a look around and catch our breaths before embarking on the next leg. We are at such a point now and this meeting I am sure will give direction to the road ahead into the decade of the seventies. In looking around at this point, 1979, it is obvious to all of us that the environment in which we must mine, mill, smelt and refine lead and zinc has radically changed. These changes have, of course, occurred over a long period of time. They have, however, all been in the same general direction. They have all had the same motivation. The period of greatest contrast is probably the fifteen years just before World War II and the fifteen years following the end of that war. I thought that I might review briefly with you what seems to me to be four of the more important changes that have developed since World War II that profoundly affect our activities in the lead and zinc industry. I mentioned before that all these changes have been in the same direction; that is, they have all tended to restrict our freedom of action in pursuing our objective of producing lead and zinc on a competitive basis at a profit. Consequently, in discussing them you may think that I am merely viewing with alarm. This is not the intent. This is merely supposed to be an objective analysis. I think it appropriate before discussing these trends in detail to examine the position of lead and zinc today.

Jan 1, 1970

By Frederick Tickell

PETROLEUM engineers are displaying considerable interest in those fundamental properties of matter and energy that control the phenomena of oil and gas production. The subject is a difficult one to investigate by laboratory experiments for two reasons: (1) it is impossible to reproduce in the laboratory the scale of forces and dimensions that exist in the underground reservoir; (2) if we attempt to scale down the dimensions we are unable to reduce all proportionally. It is as if we tried to construct a model blast furnace for the reduction of iron ore, and reduced all lineal dimensions. We should find that the interstices between the miniature chunks of ore would not .permit rapid transfer of gases, that combustion and heat transfer would not take place as in the full size furnace and that, in short, the contraption would not work. Just so, when we attempt to make a reduced scale oil field we find we must have, not only miniature reservoir and miniature wells, but "miniature" sand, oil, gas, etc. Much valuable work, however, has been done along these experimental lines and more will no doubt follow, but investigators should bear this point in mind and strive to attain dimensional homogeneity and dynamical similarity in order that their conclusions may be translated into terms applying to the oil reservoir. As Gibson says,1 "These conditions are attained when all terms of the physical equation have the same dimensions, . . . when all corresponding particles of the two systems trace out similar paths and when the velocities are such as to make all corresponding forces acting on two such particles in the same ratio. It is the purpose of this paper to discuss the mechanics of fluid movement as it pertains to the oil pool and to point out the complexity of the laws of fluid delivery under the conditions often found.

Jan 1, 1928

By Y. C. Kim, S. L. Barua

M. Armstrong's paper is very interesting and can be regarded as a pioneering work of applying geostatistics on washed coal. The density levels used in her study are uniformly spaced, which facilitated curve fitting through a proper experimental design. Most of the existing coal washing plants in the US, however, gather washability data at non-uniform intervals which, in turn, affects the goodness of curve fitting. We would like to emphasize the importance of having a proper experimental design, if a similar geostatistical application is to be conducted on washed coal. We, at the University of Arizona, tried the variogram on recovery (Kim, Barua, and Baafi, 1982, SME preprint 82-143) which showed a similar pattern as Fig. 4 of Armstrong's paper. In both cases, the first experimental variogram value is invariably and inexplicably higher than the second variogram value. Although Armstrong ignores the first point because of "small number of sample points," we did not do so because there were 17 sample pairs. As a consequence, we concluded that the obtained experimental variogram was unsatisfactory and that further research is warranted. In other words, this disagreement in variogram interpretation between M. Armstrong and the University of Arizona begs the question whether the experimental variogram of Fig. 4 truly reflects the spatial correlation in washed coal, assuming there is such a correlation. Finally, we wish that Armstrong could have done a similar study on clean sulfur, which is a vital interest to the coal mines in the US. Her implied remark on sulfur in the concluding section of the paper may turn out to be incorrect because our experimental variograms on clean sulfur at different density levels were even less satisfactory than those on recovery. ?

Jan 1, 1986

THE Section on Aerial Geologizing of the American Institute of Mining and Metallurgical Engineers convened on Monday afternoon, Feb. 17, 1936, during the Annual Meeting of the Institute. Mr. Theodore Marvin presided. CHAIRMAN MARVIN.-We hope to get through with the papers on the program in time so that you can examine the instruments that are dis-played here, and also the photographs and air views brought by the Fairchild people. This is what we might call the first bread and butter session "of the Aviation Committee. The group, as many of you know, was started at the request of the Board of Directors two years ago. We have had two sessions since then, both of them of a somewhat general nature, their pur-pose being to point out the reasons why mining and petroleum engineers should be more interested in the facilities of aviation. Today we have two papers. The first is one by Mr. Eliel, of the Fairchild Company's California branch. In Mr. Eliel's absence, Mr. Gale, of the Fairchild Company, will read it. C. H. GALE.-Before I begin to read Mr. Eliel's paper, I would like to point out two instruments that he mentions. One is what he calls the solar-navigator, a new type of aerial navigating device which he has developed for use in flying cameras in aerial surveys. Flying a camera at high altitudes over unfamiliar territory is a very difficult procedure and only a few pilots in this country can do it. So far as I know, this is the first time this device has been discussed in public. Another facility I want to refer to in advance is the use of the stereoplanigraph in making contour maps from photographs. This is an extremely interesting procedure, which we are appreciating more than ever at the present time.

Jan 1, 1936

The Section on Aerial Geologizing of the American Institute of Mining and Metallurgical Engineers convened on Monday afternoon, Feb. 17, 1936, during the Annual Meeting of the Institute. Mr. Theodore Marvin presided. Chairman Marvin.—We hope to get through with the papers on the program in time so that you can examine the instruments that are displayed here, and also the photographs and air views brought by the Fairchild people. This is what we might call the first bread and butter session of the Aviation Committee. The group, as many of you know, was started at the request of the Board of Directors two years ago. We have had two sessions since then, both of them of a somewhat general nature, their purpose being to point out the reasons why mining and petroleum engineers should be more interested in the facilities of aviation. Today we have two papers. The first is one by Mr. Eliel, of the Fairchild Company's California branch. In Mr. Eliel's absence, Mr. Gale, of the Fairchild Company, will read it. C. H. Gale.—Before I begin to read Mr. Eliel's paper, I would like to point out two instruments that he mentions- One is what he calls the solar-navigator, a new type of aerial navigating device which he has developed for use in flying cameras in aerial surveys. Flying a camera at high altitudes over unfamiliar territory is a very difficult procedure and only a few pilots in this country can do it. So far as I know, this is the first time this device has been discussed in public. Another facility I want to refer to in advance is the use of the stereoplanigraph in making contour maps from photographs. This is an extremely interesting procedure, which we are appreciating more than ever at the present time.

Jan 1, 1937

By NONE N/A

THE Section on Aerial Geologizing of the American Institute of Mining and Metallurgical Engineers convened on Monday afternoon, Feb. 17, 1936, during the Annual Meeting of the Institute. Mr. Theodore Marvin presided. CHAIRMAN MARVIN.-We hope to get through with the papers on the program in time so that you can examine the instruments that are dis-played here, and also the photographs and air views brought by the Fairchild people. This is what we might call the first bread and butter session of the Aviation Committee. The group, as many of you know, was started at the request of the Board of Directors two years ago. We have had two sessions since then, both of them of a somewhat general nature, their pur-pose being to point out the reasons why mining and petroleum engineers should be more interested in the facilities of aviation. Today we have two papers. The first is one by Mr. Eliel, of the Fairchild Company's California branch. In Mr. Eliel's absence, Mr. Gale, of the Fairchild Company, will read it. C. H. GALE.-Before I begin to read Mr. Eliel's paper, I would like to point out two instruments that he mentions. One is what he calls the solar-navigator, a new type of aerial navigating device which he has developed for use in flying cameras in aerial surveys. Flying a camera at high altitudes over unfamiliar territory is a very difficult procedure and only a few pilots in this country can do it. So far as I know, this is the first time this device has been discussed in public. Another facility I want to refer to in advance is the use of the stereoplanigraph in making contour maps from photographs. This is an extremely interesting procedure, which we are appreciating more than ever at the present time.

Jan 1, 1936

By George W. Maynard

In the biographical notice of Thomas F. Witherbee, published in.Bulletin NO. 32, August, 1909 (p. xxv), it is said that "he is believed to have been the first manager in America to use the chemical laboratory for the purpose of controlling the regular running of the blast-furnace." Since the year is not given, I cannot decide as to Mr. Witherbee's priority; but the statement leads me to contribute a bit of history, showing an early departure from the " rule-of-thumb " blast-furnace work to the employment of a chemist. In the autumn of 1868 the department of mining and metallurgy was established at the Rensselaer Polytechnic Institute. In connection with the assay-department a laboratory was equipped for making general commercial analyses. In January, 1869, Alexander L. Holley, the manager and builder of the Bessemer plant at the Rensselaer Works of John A. Griswold & Co., the first plant erected in the United States under the Bessemer patents, began to send me samples

Jan 1, 1911

The following list comprises the names of those persons who became members during the period May 10, 1916, to June 10, 1916: ARCHIBALD, JOHN CHRISTIE, Min. Engr., Supt. of Cyanide Plant, Guanajuato Reduction Mines, Guanajuato, Mex. BRUNEL, FRANK P., Cons. Min. Engr Mitchell & Brunel, Ajo, Ariz. CALVERT, WILLIAM ROBERT, Cons. Geol. ...225 Kearns Bldg., Salt Lake City, Utah. CHAMPION, J. R., Supt The Yak Mining, Milling & Tunnel Co., Leadville, Colo. CHARLES, LAVERN JOHN, Construction Engr., Elephant Butte Dam, Elephant Butte, N. M. CHASTEL, ANDRE, Min. Engr., Societe Miniere & Metallurgique de Penarroya, 12, Place Vendome, Paris, France. CHRISTIE, WALLACE H., Vice-Pres. and Mgr., Alt. Bert Gold Dredging Co., 604 Mission St., San Francisco, Cal. CLARK, RONALD ..Hardinge Conical Mill Co., 120 Broadway, New York, N. Y.

Jan 7, 1916

By Axel Hultgren

IN ingots of silicon-killed carbon steel made without addition of - aluminum, transparent spherical or nearly spherical inclusions, up to about 0.15-mm diameter, are generally present. They may be glassy or crystallized, wholly or partially. In steels of high carbon contents they consist of silica,4,12 in steels of lower carbon contents arid, in consequence, higher oxygen contents, of iron-manganese-silicate with higher iron and manganese contents the lower the carbon content. Small silicate inclusions, about 0.01 mm or smaller, may occur, just as sulphide inclusions do, in portions that have been the last or nearly the last to freeze,10,12,17 this location being verified by primary etching.10 Hence, it may be concluded that they have separated from liquid steel that has become enriched in oxygen through segregation during freezing. Silicate inclusions with a diameter larger than about 0.02 mm appear, at least in ingots of moderate size, to be distributed at random in relation to the primary structure and therefore may be assumed to have existed as droplets in the liquid steel before freezing started at the point in question. The average size of such large inclusions has been found to increase toward the axis17 and their amount to increase from the top downward in the axial region .2,10 It has been assumed that this accumulation is a result of the droplets being brought down by the slowly settling metal crystals.2 It has been suggested that large silicate inclusions generally form,6 or may form," by coagulation of smaller ones, or by small drops being caught by larger ones during the rising of the latter.9 The occasional occurrence of a large inclusion surrounded by a swarm of small ones has been taken as a proof of this mechanism but, as suggested later, may be explained in another way. It has been pointed out that an inclusion droplet in the liquid steel may grow at the expense of an adjacent one, which implies diffusion of soluble inclusion-forming elements in the liquid steel.15 Further, it has been pointed out that, on cooling in ladle or mold, the metal-silicate equilibrium is displaced in the direction of separation of silicate. Thus inclusions may grow in size and amount.2,3,8,12,13,17,19,20 The exposure of the liquid steel to the oxygen of the air during tapping and pouring, and the consequent reaction, has been mentioned as a source of the formation of inclusions19,20 but this possibility has not received particular attention. Further, the admixture of furnace slag during tapping' or of refractory material from various sources1,20 has been considered. The inclusions due to the latter may be recognized, however, through their resistance to hydrofluoric acid, imparted by the alumina content. Silicate inclusions, are often referred to as. the natural and inevitable product of reaction on adding silicon or silicon

Jan 1, 1948

By H. S. Choi, I. Iwasaki

The effect of temperature as a parameter in ore flotation has not been systematically studied, although for some ores it has been known for many years that selectivity and grade of concentrates can be improved by conditioning or flotation at moderately or substantially elevated temperatures. In 1934 Coghill and Clemmer' stated that "elevated temperature seems to make hard water more tolerable" in soap flotation, and a cursory examination of the literature indicates that some earlier investigators were aware of beneficial results obtained by floating above room or mill-water temperatures. Tartaron,2 Mitchell et aL.,3 and particularly Hamilton et al.' have shown that high pulp temperatures give high recovery and selectivity in soap flotation of fluorite from a variety of gangue minerals. As a result of the work of these and of other investigators, high-temperature flotation has been successfully applied to industrial flotation of fluorite. Falconer" stated: "The use of high temperature conditioning (above 35°C and preferably above 60°C) in connection with the soap flotation of nonsulphide ores, as covered in B. Kalinowski's French Patent No. 847,-215, Dec. 7, 1938, is claimed to provide more intense activation, better separation of values from gangue, and reduction in quantity of reagents." The various investigations quoted above clearly demonstrate the improvements to be realized by increasing the temperature at which fluorite is floated, and it is surprising that little or no information has been published on systematic investigation of the same method as applied to other ores. The present article describes comparative results obtained at room temperature and at elevated temperatures by otherwise conventional flotation of iron ores, by single-mineral flotation in the Hallimond tube, and by contact-angle measurements. It is not the purpose of this article to evaluate the commercial feasibility of high-temperature flotation of iron ores, although preliminary calculations show that the cost should not be excessive and that the gains to be realized may well outweigh the extra cost of heating the pulp. LABORATORY FLOTATION TESTS Experimental: All flotation tests reported in this article that use a laboratory Fagergren cell were made on ore A (either containing the primary slimes or deslimed at 20µ as specified) following the preparatory procedures described elsewhere- or this particular ore. Ore A contained hematite, goethite (limonite), quartz, chert, and minor quantities of magnetite. Confirmatory tests made on other ores show that the same general principles apply to ores of similar mineralogy and structure. Conditioning was performed by adding the collector, as a soap, to the vigorously stirred and heated pulp. Conditioning time was 5 min, the pulp contained 60 pct solids, and the equivalent of 0.5 Ib of fatty acid was added per ton of original (unde-slimed) ore. The pH of the pulps ranged from 6.8 to 7.1 (25°C measurement) during conditioning. The pH was adjusted in the flotation cell by addition of either NaOH or H2SO4, the values reported being those of the pulp cooled to 25°C. During conditioning and flotation the pulp temperatures were controlled within l° to 2° by immersion of Variac-controlled Calrod elements in the conditioning beaker and in the cell, and by the use of water, heated to the appropriate temperature, for transferring pulp, adjusting pulp volume, and washing. Selectivity indexes have been calculated on the same basis as those reported in the article by Cooke, Iwasaki, and Choi." Results: Table I gives the results obtained by floating deslimed ore A with pure oleic acid at 25" and 50°C, and Fig. 1 shows the selectivity indexes plotted against pH of flotation. Inspection of Table I

Jan 1, 1961

By J. B. Wagner, B. Swaroop

The atomic ratios of oxygen to iron in zlarious corn-posilions of wustite in the vicinity oj the reported p to n transformation were determined in the temperalure range between 950" and 1250°C. For these conditions, equilibrium vacancy concenrations have also been determined at vatious mixtures of C0,-CO. The data show a continuos introduction of iron vacancies as oxygen is introduced into wuistite. No phase change is observed with in the wuustite field. However, the value of n in the isothermal oxygen pressure dependence, the weight change shifts to 1ower values as the concentration of oxygen increases. WUSTITE is a metal deficit semiconductor with the majority lattice disorder being cation vacancies. Using the notation similar to that of Kroger and ink,' the dissolution of oxygen into wiistite using C02-CO mixtures is represented by, WHere v+! denotes a cation vacancy with k effective negative charges and kh • denotes k electron holes, h -. Applying the law of mass action and assuming a dilute solution of defects in the wiistite yields Where the square brackets denote concentrations. Furthermore, when k = 2 the cation vacancies are completely ionized, and both the concentration of cation vacancies and the concentration of electron holes are proportional to the third root of the ratio, PC /PCo. This analysis is valid for one particular mael based on an ideal solution at elevated temperatures (in this case t > 1000°C). At lower temperatures, it has been shown2 that the pressure dependence of the electronic conductivity changes in a manner which suggests that vacancies interact with or "trap" electron holes. At the very high concentrations of defects, 10'' to 10" per cu cm, these simple models no longer hold. Recently Tannhauser,3 Geiger et a1.' Bransky and Tannhauser; and Hillegas' have found an apparent p to n transformation in wiistite in the temperature range of 950" to 1300°C. This junction was found by thermoelectric and electronic conductivity measurements. Geiger eta1.' found that the electronic conductivity became almost independent of the oxygen pressure at high temperatures and oxygen concentrations within the experimental error. In addition, Vallet, Raccah, and coworkers6'7 have reported the existence of several "varieties" of wiistite which were reported to exist within what was heretofor presumed to be a

Jan 1, 1968

By A. W. Schillinger

Drilling was not entirely satisfactory in the search for native copper in the Osceola amygdaloid footwall, for oreshoots mined were more continuous than drilling indicated. The Geophysics Dept of Michigan Technological University developed a portable induced polarization drill hole probe with a 3-electrode configuration and a sampling radius of 5 ft ±. A 20 ma current of alternately reversed polarity is pulsed at 3.5 sec intervals and readings are taken every 2 ft. Potential is read during the "on" cycle for resistivity determinations. During the "off" cycle, after 10 ms delay, the 1P potential is sampled for 10 ms and recorded. Resistivity (ohm-ft) and "S" values (mv/v) are plotted on semi-log paper. A lithologic log is plotted based on resistivity and anomalous S values noted. The low resistivity amygdaloid contains sills of high resistivity basalt. Verified by core logs, contacts between amygdaloid and basalt could be picked to ± 0.5 ft from resistivity alone. Lithologic logs of long-steel holes, based on resistivity, then replaced sludge logging. An S value of 30 mv/v was established as the lower limit of diagnostic 1P effects in mineralized amygdaloid and 50 mv/v as a threshold value for ore. Of 914 footwall zones drilled, 315 were probed yielding 203 anomalies. Success increased from 34% for drilling to 72% for drilling and probing. As checked by mining, 46 probe results were 78% correct. Failures were due to the instrument not detecting copper or to the misinterpretation of an anomaly. No false anomalies were found. During the past ten years, the Calumet Div. of Calumet &Hecla, Inc has conducted extensive exploration and mining in the footwall of the Osceola amygdaloid lode in the native copper district in Michigan's Upper Peninsula. In an attempt to delineate more clearly the extent and nature of high-grade footwall copper mineralization, 876 diamond drill and long steel holes aggregating slightly more than 47,000 ft have thus far been drilled from the accessible hanging-wall workings in the Osceola No. 6, 13, 14 and 15 shafts. Early in this program it became obvious, through inspection of footwall workings in progress, that due to the erratic and bunchy occurrence of the native copper in the footwall zone, the exploration drilling was failing to outline completely the extent of the oreshoots. Early drilling re-

Jan 1, 1964

By C. C. Templeton, S. S. Rushing

Methods previously developed for the study of air-liquid displacements in microscopic capillaries (inner diameters of 3 to 40 microns) have been used to investigate oil-water displacements in capillaries initially filled with water. Displacement calculations assuming perfect displacement and no capillary pressure hysteresis yielded oil effective viscosities smaller than the macroscopic viscosities. For a given liquid pair, the oil effective viscosity decreased both with decreasing capillary size and with increasing oil-water viscosity ratio. This behavior can be explained by the existence of an annular water film (20 A to 260 A thick) on the capillary wall. When the capillary was first filled with oil, the ratio of the oil effective viscosity to the normal oil vircosity was highest for the first water displacement and decreased with subsequent displacements. Sometimes the oil effective viscosity ratio during the initial water displacement was greater than unity. INTRODUCTION In a previous paper1 a technique was described for studying air-liquid and liquid-liquid displacements in very small capillaries of uniform diameter, in the hope that such microscopic data would further the understanding of the nature of multiphase fluid flow through porous media. That paper contained comprehensive data for air-liquid displacements in Pyrex capillaries, with a few data for oil-water displacements in capillaries initially filled with water. The purpose of this paper is to present more complete results for oil-water displacements in capillaries initially filled with water, and to describe for the first time such observations in capillaries initially filled with oil. In this way the effect of the wetting history of the system upon the displacement process may be studied. METHODS The basic techniques employed were described in the previous paper.1 The measuring procedure and the working equations will be briefly summarized here and a few modilications will be pointed out. For the present study, temperature control within 0.l °C was obtained by placing the microscope and its immediate accessories in a thermostated air bath made of a steel frame covered with plexiglas. The water and oils used in this work were the same as in the previous paper,1 with the addition of "Medium Mineral Oil, U.S.P. supplied by the Harshaw Scientific Co. When the first liquid was introduced into the horizontal capillary, the air-liquid static capillary pressure Poc was measured along the observable length of the capillary. From the relation Poc = 4y cos 0/d, the capillary diameter d could be calculated from Poc if the "microscopic" air-liquid boundary tension, To = y cos On, was taken as equal to its known "macroscopic" value. This calculation involves assuming that cos 6 = 1 and that capillary size or the resulting high interfa-cial curvature has no effect on surface tension, or y cos 6, as was verified by our work, and also by that of Cohan and Meyers on air-liquid-solid systems. For several capillaries these calculated diameter values were compared with values measured visually with a filar micrometer eyepiece. For a given capillary the average values for the two methods agreed within 1 or 2 per cent, but the visual values were less reproducible than the calculated values. Further the calculated values were much less subject to personal bias and took into account any slight ellipticity that might be present. Hence diameters calculated from air-liquid Poc data were used throughout this paper. The second liquid was introduced in such a way that a single spherical interface separated the two liquids. Displacements were always made with a constant pressure, Pt, between the ends of the capillary. The times (t) at which the interface passed certain

Jan 1, 1957

By E. H. Kelton, R. D. Grissinger

E. E. Schumacher.*—DO YOU control the humidity in your test room? What effect does the environment have on your results? E. H. Kelton.—We do not attempt to control the humidity. As a matter of fact, the humidity in the beam tests that were conducted in a constant-temperature room varied widely and, as far as we know, there is no effect. The tension tests were conducted largely in an oil bath. I suppose there would be an effect in highly corrosive atmospheres, sufficiently corrosive to notch the specimen; otherwise, I would say none. E. A. Anderson.*—The effect of the humidity on the corrosion of zinc does not become important until the relative humidity is 70 per cent. At that point the corrosion products are capable of absorbing moisture and the corrosion rate increases. Below that point corrosion is almost imperceptible. This does not take into account any effect due to stress. That may be important. E. E. Schumacher.—Recently 1 have become very conscious of the enormous effect that surface films can exert on the physical properties of certain alloys. Shortly, we are publishing an article in which it will be shown that the fatigue endurance of some lead alloys can be changed markedly by merely changing the type of film placed on their surfaces. Changes as great as tenfold were observed. These findings make me wonder whether in your creep test you might not obtain quite variable results, depending upon the type of liquid medium used to immerse your specimens. Did you use more than one type of oil and, if you did, what were your results? E. H. Kelton.—I think we have used no more than three different oils, and we could not see any difference in effect.

Jan 1, 1945

By E. Mcl. Tittmann

Deep-seated human instincts urge us to positively mark the passage of time. We celebrate the passage of each year. Years give way to decades, and decades to half centuries and centuries. At all these mileposts we are inclined to pause, take a look around and catch our breaths before embarking on the next leg. We are at such a point now and this meeting I am sure will give direction to the road ahead into the decade of the seventies. In looking around at this point, 1973, it is obvious to all of us that the environment in which we must mine, mill, smelt and refine lead and zinc has radically changed. These changes have, of course, occurred over a long period of time. They have, however, all been in the same general direction. They have all had the same motivation. The period of greatest contrast is probably the fifteen years just before World War II and the fifteen years following the end of that war. I thought that I might review briefly with you what seems to me to be four of the more important changes that have developed since World War II that profoundly affect our activities in the lead and zinc industry. I mentioned before that all these changes have been in the same direction; that is, they have all tended to restrict our freedom of action in pursuing our objective of producing lead and zinc on a competitive basis at a profit. Consequently, in discus- sing them you may think that I am merely viewing with alarm. This is not the intent. This is merely supposed to be an objective analysis. I think it appropriate before discussing these trends in de- tail to examine the position of lead and zinc today.

Jan 1, 1970

By J. J. Gilman

Zinc monocrystals, when compressed nearly parallel to their basal planes (within 20), deform in a new way; and certain deformation markings, called "-bands," are typical of this new mode. Characteristics of these bands are described. Mechanical behavior of low angle zinc monocrystals was investigated in some detail. Recrystallization did not occur upon annealing of banded specimens that were free of deformation twins. -Bands do not seem to be the result of nonbasal slip, but rather, a result of a microbuckling mechanism. u-Bands differ qualitatively and quantitatively from ortho kink bands. A dislocation model, consistent with some of the features of u-bands, is described. THE plastic deformation of zinc monocrystals with slip planes (0001) nearly parallel to the stress axis was studied in this investigation. In a previous investigation, it was shown that some low angle zinc crystals (those with slip planes making angles of more than about 2.5+1° with the compression axis), deform by ortho kinking while others (those with slip planes making angles of less than 2.5+1° with the compression axis) deform in a new way.' This new mode of deformation will be described in some detail here. Some of its striking features are: 1—it operates only for compressive stresses, 2—its temperature dependence is anomalous, and 3—it exhibits a new type of "yield-point" behavior. The mode of deformation to be discussed is not new in the sense that no previous evidence of its existence had been reported. The markings that it creates on the cleavage surfaces of zinc crystals have been described by several investigators.'" However, this is the first time that it has been made to operate under controlled conditions so that its response to mechanical variables, temperature, and aging treatments could be investigated and its geometry completely described. Apparently. Jillson' as well as Holden3 and Pratt" believed that the small bands they observed were simply small versions of ortho kink bands. In fact, two of these authors3,6 "alled the markings "micro kink bands." In spite of the precedence, it is felt that this term is not entirely suitable because these bands do not have the same genesis as kink bands, and they are qualitatively different in structure. As will be indicated by later discussion, the bands seem to be related to the tensile deformation bands observed in aluminum. The present author has chosen to call the bands "micro deformation bands," or simply ",ubands," and the deformation process, ''p-banding." Experimental Methods Crystals were grown from 99.999+ pct Zn obtained from the New Jersey Zinc Co. The details of the technique are given elsewhere." It should suffice to say that the crystals were seeded for orientation control, and precision pyrex tubes were used for molding them. About 40 crystals were used, yielding some 130 specimens. Fig. 1 illustrates the typical form of the specimens and shows how the orientation angles are defined. The crystal specimens were usually 1 3/4 in. long and about 150 mil in diameter. The angle between the slip or cleavage plane (0001) and the specimen axis is designated by xo, while a is the angle between the maximum slope of the (0001) plane and the nearest close-packed direction [1210], vary ing from 0°to 30°. The crystals were cut into specimens with a jeweler's saw and the ends were squared by filing (specimens held in V-block). Crystals of this orientation are stiff toward bending, so this procedure introduced only deformation localized at the ends. Then the specimens were polished either chemically in 50 pct HNO³ or electrolytically in 20 pct chromic acid. The mechanical tests were made with an Instron testing machine. This machine weighs by means of electric strain gages on elastic bars and is quite stiff, since the full-load deflection of its load cells is at most 0.002 in. Most of the testing was done at a

Jan 1, 1956